The present invention generally relates to an automotive vehicle body structure for improving the vehicle crash safety, and in particular to a seat belt pretensioner device which is powered by a relative displacement between two parts of the vehicle body at the time of a vehicle crash.
In recent years, with the aim of improving the safety of vehicle occupants at the time of a vehicle crash, various vehicle body structures have been proposed in which the deformation mode of the part of a vehicle body other than the passenger compartment is appropriately controlled in such a manner that the deceleration of the passenger compartment of the vehicle is reduced, and the deformation would not reach the passenger compartment (Japanese patent laid-open publication No. 07-101354 and others).
At the time of a vehicle crash, the deceleration of a vehicle occupant who is restrained to a vehicle seat by an occupant restraint system such as a seat belt rises sharply only when the forward inertia force acting on the occupant is received by the seat belt. As it is not possible to eliminate the tendency of the seat belt to act as a spring, the vehicle occupant moves forward under the inertia force, and the deceleration of the vehicle occupant reaches the peak value when the elongation of the seat belt reaches the maximum value. The greater the displacement of the vehicle occupant under the inertia force, the higher the peak value of the vehicle occupant becomes, and the peak value of the vehicle occupant acceleration is said to exceed the average deceleration of the vehicle body.
In view of minimizing the injury to the vehicle occupant at the time of a vehicle crash, the maximum acceleration (deceleration) of the vehicle occupant should be reduced. The vehicle occupant deceleration is dictated by the waveform (time history) of the vehicle body deceleration when the vehicle occupant is held integrally with the vehicle body by the seat belt. As shown in FIG. 9, to minimize the vehicle occupant deceleration (G1), a preferred waveform (G2) of the deceleration of the vehicle body (seat) should consist of an initial interval (a) characterized by a high deceleration, an intermediate interval (b) characterized by an opposite deceleration, and a final interval (c) characterized by an average deceleration.
To achieve such a waveform, proposals have been made in copending U.S. patent application Ser. No. 09/377,366 now U.S. Pat. No. 6,186,574 and Ser. No. 09/376,888 now U.S. Pat. No. 6,193,296 both filed on Aug. 18, 1999, to impart a relative deceleration and acceleration to the vehicle seat or the member carrying the vehicle seat with respect to the main part of the vehicle body so that the vehicle occupant may experience a deceleration from an early stage of a vehicle crash, and the maximum vehicle occupant deceleration may be reduced by distributing the inertia force acting on the vehicle occupant over a longer period of time. Similar proposals have been made in additional copending patent applications. This can be accomplished either by using a power actuator or solely through the controlled deformation of the various members of the vehicle body including that of the G-control member. The contents of these applications are hereby incorporated in this application by reference.
In such an arrangement, if there is any excessive slack in the seat belt, even though the seat may undergo a relatively controlled time history of deceleration itself, the failure to properly restrain the occupant causes a delay in the time history of deceleration for the occupant, resulting in a relatively sharp rise in the occupant""s deceleration level as the seat belt finally becomes effective in restraining the occupant. In other words, for such an arrangement to be effective, it is essential to provide a suitable seat belt pretensioner system so that the occupant may be effectively restrained to the occupant seat from an early phase of a crash.
When a G-control member is used in a vehicle body, the vehicle body not only deforms in a controlled manner but also a controlled relative displacement occurs, in particular, between the G-control member and the rest of the vehicle body. Such a displacement can be conveniently used as a power source for a seat belt pretensioner device. This can be accomplished by providing at least one of the anchor points of the seat belt in a part of the vehicle body which is not part of the) G-control member.
This however may create an inconvenience because the position of the anchor point may significantly change as the position of the occupant seat is adjusted in the fore-and-aft direction to accommodate for the difference in the build of the occupant and ensure the comfort of the occupant. For instance, if the anchor point is provided in the rear end of the seat slide so as to ensure the function of the restraint system over the entire range of the seat slide movement, some problems arise when the seat is placed at the front most position because the anchor point is so far away from the vehicle occupant that the vehicle occupant experiences some difficulty in reaching the anchor point which may consist of a buckle provided with a latch device that needs to be manually operated.
In view of such a recognition by the inventors, a primary object of the present invention is to provide a seat pretensioner device which does not require any power source.
A second object of the present invention is to provide a seat pretensioner device which enhances the performance of a G-control vehicle body which minimizes the peak value of the deceleration for the vehicle occupant at the time of a vehicle crash.
A third object of the present invention is to provide a seat pretensioner device which makes use of a relative displacement between two parts of the vehicle body, but allows the fore-and-aft adjustment of the seat without causing any inconvenience.
According to the present invention, such objects can be accomplished by providing a seat belt pretensioner device for a seat belt having a plurality of anchor points attached to different parts of a vehicle body, the vehicle body including a G control vehicle body member which deforms in a different pattern from a remaining part of the vehicle body at the time of a vehicle crash; wherein: at least one of the anchor points, which typically consists of a seat belt buckle, is attached to the G control vehicle body member via a force transmitting member which is adapted to move the one anchor point in a direction to increase a tension of the seat belt at the time of a vehicle crash.
Thus, a seat belt pretensioner device can be achieved in a simple manner without requiring any special power actuator. According to a preferred embodiment, the power transmitting member comprises a flexible member such as a cable member having one end attached to the G control member, and an anchor point guide member supporting the anchor point and having another end of the cable member attached thereto, the anchor point guide member being adapted to move in a direction to increase a tension of the seat belt. Thus, it is possible to use a relative displacement of vehicle body parts which may be significantly remote from the anchor point in question.
The anchor point is required to be guided to move along a prescribed path, and it can be readily accomplished if the anchor point guide member comprises an arm member pivotally supported by a seat and having the anchor point attached to a free end thereof. The arm member may also consist of a pulley member. In this case, the cable member may be passed around an arcuate section of the pulley member for a desired motion of the anchor point.
A vehicle seat is normally required to be adapted to fore-and-aft adjustment, and this should not interfere with the pretensioner device of the present invention even when the anchor point is integral with the vehicle seat. If the anchor point guide member comprises a pulley member, the movement of the anchor point that is caused by the fore-and-aft adjustment of the vehicle seat can be minimized by controlling the way the cable member is paid out from the arcuate section of the pulley member.
The G control member may take a number of different forms without departing from the principle of the present invention. For instance, the G control member may be disposed under a floor panel while the cable member is attached to the G control member at one end thereof, and is passed through an opening formed in the floor panel to be attached to the anchor point guide member.
According to a preferred embodiment of the present invention, the seat is connected to the G control member, and the cable member is connected between the anchor point guide member and the G control vehicle body member, a cable guide member being provided in the opening of the floor panel and adapted to push an intermediate part of the cable member at the time of a vehicle crash. In this case, a seat adjustment arrangement may be provided between the seat and the G control member.
Alternatively, the seat may be attached to the floor panel while the cable member is connected between the anchor point guide member and the G control vehicle body member, a cable guide member being provided in the opening of the floor panel and adapted to push an intermediate part of the cable member at the time of a vehicle crash. In this case, a seat adjustment arrangement may be provided between the seat and the floor panel member.